1. Field of the Invention
The present invention relates to a resinous tube which is used for distributing fuels, coolants, and the like.
2. Description of the Related Art
Resinous tubes exhibit a higher rigidity than rubber tubes, and so on. Moreover, when the resinous tubes are provided with a bellows, or the like, they show a high degree of freedom in piping arrangements. Accordingly, the resinous tubes are used as members which make filler pipes, radiator hoses, and so forth.
However, when resinous tube are used, there arises the problem concerning the connecting mechanisms with the mating members, such as pipes, hoses, and so on. Namely, the resinous tubes exhibit rigidity to a certain extent. Accordingly, compared with rubber tubes, etc., it is less likely that the resinous tubes securely exhibit adherence with respect to the mating members. When the adherence is low, the sealing ability between the resinous tubes and the mating members lowers. Moreover, the fastening ability between the resinous tubes and the mating members lowers so that the resinous tubes are likely to come off from the mating members.
Hence, the sealing ability and the fastening ability have been conventionally secured between the resinous tubes and the mating member by means of the following connecting mechanisms described below.
FIG. 5 illustrates a cross sectional view of a connecting mechanism by means of a snap-action connector (hereinafter referred to as a “quick connector”) method which is taken in the axial direction. Note that the alternate long and short dash line specifies the axial central line in the drawing. Moreover, since the opposite side (i.e., the lower side in the drawing) is symmetric linearly with respect to the axial center line, it is not illustrated. As illustrated in the drawing, the connecting mechanism secures the sealing ability and the fastening ability by intervening a quick connector 202 between a resinous tube 200 and a mating member 201. The quick connector 202 comprises a housing 205, sealing rings 204 and a retainer 203. The housing 205 is formed as a cylinder shape, and has a minor diameter portion and a major diameter portion. The minor diameter portion of the housing 205 is fitted into an opposite end of the resinous tube 200 by pressing. Thus, the sealing ability and the fastening ability are secured between the resinous tube 200 and the quick connector 202. Further, into the major diameter portion of the housing 205, an opposite end of the mating member 201 is fitted. Furthermore, on an inner peripheral surface of the major diameter portion, the sealing rings 204 and the retainer 203 are disposed in series from the inner side toward the outer end side. The retainer 203 is formed as a letter “L” shape in cross section. On the other hand, on an opposite-end outer-peripheral surface of the mating member 201, there is disposed a flange-shaped bead 206 therearound. Thus, by engaging the retainer 203 with the bead 206, the fastening ability is secured between the quick connector 202 and the mating member 201. Moreover, by elastically bringing the sealing rings 204 into contact with the outer peripheral surface of the mating member 201, the sealing ability is secured between the quick connector 202 and the mating member 201.
FIG. 6 illustrates a cross sectional view of a connecting mechanism by means of a rubber sealing member method which is taken in the axial direction. Note that the alternate long and short dash line specifies the axial central line in the drawing. Moreover, since the opposite side (i.e., the lower side in the drawing) is symmetric linearly with respect to the axial center line, it is not illustrated. As illustrated in the drawing, the connecting mechanism secures the fastening ability and the sealing ability by intervening a rubber sealing member 302 between a resinous tube 300 and a mating member 301. The rubber sealing member 302 is formed as a cylinder shape, and is disposed between an inner peripheral surface of the resinous tube 300 and an outer peripheral surface of the mating member 301. Further, the rubber sealing member 302 is tightened by a clamp 303 from the outer peripheral side of the resinous tube 300. Furthermore, the rubber sealing member 302 exerts an elastic force and the clamp 303 exerts a tightening force so that the fastening ability and the sealing ability are secured between the resinous tube 300 and the mating member 301.
FIG. 7 illustrates a cross sectional view of a connecting mechanism by means of an engagement method which is taken in the axial direction. The connecting mechanism is set forth in Japanese Unexamined Patent Publication (KOKAI) No. 6-50,482. Note that the alternate long and short dash line specifies the axial central line in the drawing. Moreover, since the opposite side (i.e., the lower side in the drawing) is symmetric linearly with respect to the axial center line, it is not illustrated. As illustrated in the drawing, sealing rings 101 are assembled around an opposite end of a resinous tube 100. Further, on an outer peripheral surface of the resinous tube 100, there are disposed engagement claws 102 at predetermined angular intervals. On the other hand, at a terminal end of an opposite end of a mating member 103, there is disposed an engagement portion 104. The engagement portion 104 is formed as a letter “U” shape in cross section by bending. When the resinous tube 100 is fitted into the mating member 103, the engagement claws 102 engage with the engagement portion 104. By the engagement, the fastening ability is secured between the resinous tube 100 and the mating member 103. In addition, when the resinous tube 100 is fitted into the mating member 103, the sealing rings 101 are brought into contact with an inner peripheral surface of the mating member 103 elastically. Note that the sealing rings 101 are disposed in sealing ring retainer grooves 105 which are formed in the outer peripheral surface of the resinous tube 100. By the elastic contact, the sealing ability is secured between the resinous tube 100 and the mating member 103.
However, when the conventional connecting mechanism illustrated in FIG. 5 is used, since it is necessary to independently dispose the quick connector 202, it results not only in raising up the cost but also in increasing the number of the component parts. Moreover, the man-hour requirements for bonding the resinous tube 200 with the mating member 201 are thereby enlarged. In addition, it is required to form the bead 206 on the mating member 201 for the engagement with the retainer 203. In other words, by the quick connector 202, it is not possible to connect a resinous tube with mating members which are free from the bead 206.
Further, when the conventional connecting mechanism illustrated in FIG. 6 is used, there arises a problem in a case where the resinous tube 300 is used for filler pipes. Namely, in the applications to filler pipes, members, such as a pipe, and the like, which make a fuel passage, are required to exhibit a low fuel permeability. The rubber sealing member 302, however, exhibits a high fuel permeability. In this instance, it is possible to think of forming the rubber sealing member 302 itself of materials, such as fluoroelastomers, and so on, which exhibit a low fuel permeability. However, the materials, which exhibit a low fuel permeability, are expensive in general. Accordingly, when the entire rubber sealing member 302 is formed of a material, which exhibits a low permeability, the cost goes up inevitably. Moreover, in this method, since one and only sealing member is responsible for both the sealing function and the coming-off inhibiting function, it is difficult to set up the material designing in view of satisfying both the sealing function and the coming-off inhibiting function at a higher level. Specifically, it is difficult to simultaneously satisfy both of the permeability and the permanent set in fatigue. In addition, when the inside diameter of the rubber sealing member 302 is reduced, the connecting mechanism suffers from the problem of the lowering operability in press-fitting.
Furthermore, when the conventional connecting mechanism illustrated in FIG. 7 is used, it is necessary to form the engagement portion 104 at the terminal end of the opposite end of the mating member 103. To put it differently, it is not possible to connect the resinous tube 100 with mating members which are free from the engagement portion 104. Moreover, the resinous tube 100 is provided with the engagement claws 102. Consequently, when the resinous tube 100 is produced, it is necessary to carry out a step of manufacturing a tube body by blow molding, and subsequently a step of bonding the engagement claws 102 with the resulting tube body by injection molding. Therefore, the production process requires so many steps that it is troublesome.
The present invention has been completed in view of the aforementioned problems. It is therefore an object of the present invention to provide a resinous tube which is good in terms of the sealing ability and the fastening ability, which requires less component parts and is accordingly less expensive, and which is connectable with mating members whatever they are.
It is possible for a resinous tube according to the present invention to achieve the aforementioned object. The present resinous tube is a resinous tube having opposite ends into one of which a mating member is fitted and with which the mating member is connected, and comprises: a sealing ring being disposed on an inner peripheral surface of one of the opposite ends, and contacting elastically with an outer peripheral surface of the mating member; a fastening cap being disposed on the inner peripheral surface of the opposite end on an outer end side thereof with respect to the sealing ring, and contacting elastically with the outer peripheral surface of the mating member; and a clamp being disposed on an outer peripheral surface of the opposite end, the opposite end being provided with the fastening cap on the inner peripheral surface, and tightening the fastening cap.
Namely, in the present resinous tube, the sealing ring and the fastening cap are disposed on the inner peripheral surface of the opposite end in series from the inner side of the present resinous tube to the opposite-end side thereof. Moreover, the clamp is disposed on the outer peripheral surface of the opposite end in order to tighten the fastening cap. Thus, the sealing ring secures the sealing ability between the resinous tube and the mating member. Simultaneously, the fastening cap and the clamp secure the fastening ability between both of the members.
It is possible to readily connect the present resinous tube with mating members which are free from the bead 206 as illustrated in FIG. 5, and which are free from the engagement portion 104 as illustrated in FIG. 7. Moreover, when the present resinous tube is connected with mating members, it is not necessary to intervene such a member as the quick connector 202 as illustrated in FIG. 5. In addition, when the present resinous tube is used for filler pipes, for instance, it is possible to suppress fuels from permeating by forming only the sealing ring of materials, which exhibit a low fuel permeability, such as fluoroelastomers, and the like. Accordingly, the present resinous tube requires a low cost for reducing the fuel permeability.
For example, it is possible to produce the present resinous tube by the following process. The process comprises the steps of: manufacturing a continuous tube body, in which tube bodies having opposite ends are disposed in series, continuously; cutting the resultant continuous tube body to the respective tube bodies; and fitting a sealing ring and a fastening cap in this order into an inner-peripheral-surface side of one of the opposite ends of the cut tube bodies.
Namely, in the production process, the tube bodies are manufactured continuously as the continuous tube body. In the present resinous tube, a component member, such as the engagement claw 102 as illustrated in FIG. 7, is not disposed. Consequently, it is not necessary to carry out the step of disposing a component member on the tube body individually. Therefore, it is possible to continuously manufacture the tube bodies by a single step, and thereby it is possible to reduce the number of the production steps. Note that, in the step of manufacturing the continuous tube body, it is possible to use an extrusion blow molding method, and so forth. In the extrusion blow molding method, air is pressurized and entered a parison, which is made from a resin and is extruded out of an extrusion molding machine, and the parison is pressed onto a molding mold in order to arrange its shape.
Moreover, it is possible to dispose the clamp on the outer peripheral surface of the opposite end of the tube bodies at any time after the step of cutting the continuous tube body. For instance, after the step of disposing the sealing ring and the fastening ring on the inner peripheral surface of the opposite end, it is possible to temporarily dispose the clamp on the outer peripheral surface of the opposite end of the tube bodies. Then, after the mating member is fitted into the opposite end of the tube bodies, it is possible to additionally tighten the clamp. Alternatively, after the mating member is fitted into the opposite end of the tube bodies, it is possible to dispose the clamp on the outer peripheral surface of the opposite end of the tube bodies. Subsequently, it is possible to tighten the clamp.
It is preferable to arrange so that the opposite end can be formed so that it has a thinner thickness at a portion on which the fastening cap is disposed than at a portion on which the sealing ring is disposed.
Namely, in such an arrangement, the opposite end of the present resinous tube is provided with a heavy-thickness portion and a thin-thickness portion. Specifically, the heavy-thickness portion is disposed at a portion in which the sealing ring is inscribed, and the thin-thickness portion is disposed at a portion in which the fastening cap is inscribed and on which the fastening cap is circumscribed, respectively.
When the heavy-thickness portion is disposed at a portion in which the sealing ring is inscribed, it is possible to enhance the rigidity of the opposite end of the present resinous tube. Moreover, when the thin-thickness portion is disposed at a portion in which the fastening cap is inscribed and on which the fastening cap is circumscribed, it is possible to transmit the tightening force of the clamp to the fastening cap without being obstructed by the thickness of the present resinous tube. Accordingly, the present resinous tube exhibits a more favorable fastening ability.
It is more preferable to arrange so that the fastening cap can have an inside diameter equal to or slightly smaller than an outside diameter of the mating member.
Namely, in such an arrangement, the inside diameter of the fastening cap is designed to a relatively large diameter. The fastening cap of the present resinous tube is tightened by the clamp from the outer peripheral side. Consequently, it is possible to readily secure a fastening ability without excessively reducing the inside diameter of the fastening cap.
In accordance with such an arrangement, the frictional force is reduced when the mating member is fitted into the present resinous tube. Accordingly, it is possible to furthermore smoothly fit the mating member into the present resinous tube.
Moreover, it is preferable to arrange so that a plurality of the sealing rings can be disposed, and so that a spacer can intervene between the sealing rings, respectively.
Namely, in such an arrangement, a plurality of the sealing rings are disposed on the inner peripheral surface of the opposite end of the present resinous tube. Then, the spacers separate between the sealing rings, respectively.
In accordance with such an arrangement, it is possible to readily carry out positioning the sealing rings by the spacers. Specifically, it is possible to readily position the sealing rings by the fastening cap and the spacers. Consequently, it is possible to obviate such portions like the sealing ring retainer grooves 105 as illustrated in FIG. 7.
In addition, it is preferable to arrange so that a ring can be further disposed on an inner side with respect to the sealing ring, so that the opposite end can be formed as such a thin thickness that it is capable of diametrically enlarging, and so that the sealing ring and the ring can be brought into contact with the inner peripheral surface of the opposite end elastically by the diametrically enlarged opposite end.
Namely, in such an arrangement, the entire opposite end of the present resinous tube is formed as such a thin thickness that it is capable of deforming elastically so as to diametrically enlarge. Moreover, the ring is disposed next to the sealing ring on an inner side of the present resinous tube with respect to the sealing ring. When nothing is fitted into the opposite end of the present resinous tube, the inside diameter of the opposite end is designed to be smaller than the outside diameters of the ring and the sealing ring. When the ring and the sealing ring are fitted into the opposite end by pressing, the opposite end is elastically deformed to diametrically enlarge. Then, the opposite end comes to tighten the ring and the sealing ring from the outer peripheral surfaces by a repulsive diametrically reducing force.
In accordance with such an arrangement, it is possible to reinforce the sealing force of the sealing ring by the repulsive diametrically reducing force. Moreover, since the ring is disposed, it is possible to suppress the rigidity of the opposite end of the present resinous tube from lowering, which results from thinning out the opposite end. Note that the opposite end can have such a thin thickness that it is capable of deforming elastically so as to diametrically enlarge. Accordingly, the desired thickness of the opposite end depends on the materials, and so forth, of the present resinous tube, the sealing ring and the ring.
In accordance with the present invention, it is possible to provide a resinous tube which is good in terms of the sealing ability and the fastening ability, which requires less component parts and is accordingly less expensive, and which is connectable with mating members whatever they are.